In many hydrocarbon well applications and other applications, pistons are employed to actuate a variety of tools and systems. In some applications, the pistons are actuated by a working or actuating fluid. In other applications, the pistons are used to move fluid: this is the case in a piston pump. During their usage, these pistons are submitted to a difference of fluid pressure between their two extremity surfaces. To contain this difference of pressure, many pistons employ seals, e.g. elastomeric dynamic seals or metal piston rings, to exclude particulates in the actuating fluid from the piston/cylinder bore interface. In some applications, e.g. wellbore drilling applications using drilling mud (either as actuating fluid or as the fluid being moved), the fluid may contain a substantial amount of hard particulates. Even with seals, the particulates can enter the clearance between the piston and the surrounding wall which often is a cylindrical wall. As a result, the particulates can damage the piston components via third body abrasion and/or completely jam the motion of the piston as the particulates embed in the piston and/or surrounding cylinder surfaces.